Effect of various collection sites on the amount of microplastics found in falling precipitation

Abstract

Plastic use has increased exponentially since the 20th century. Due to their durability and low cost, they are used in packaging, medical devices, and machinery. Plastic degrades over time into smaller microplastics (<5mm), but is not removed entirely. Microplastics (MPs) in the marine environment are entrained into the atmosphere. Then, MPs precipitate through rain or snow and flow into soils and landfills. MPs enter the body through inhalation or food consumption. Accumulating these MPs has been found to affect the human body negatively. MPs have been found in precipitation in various locations around the world, including rural areas, although this is not consistently observed. This study focuses on whether sites of precipitation collection impact the number of MPs found in the samples. Samples were collected in four different areas: under a tree canopy, in an open field, on a roof, and next to a building at Shattuck-St. Mary’s School in Faribault, Minnesota. Precipitation samples were analyzed by simultaneous transmitted polarized light microscopy (PLM), darkfield reflected light microscopy (RLM), and fourier transform infrared spectroscopy (FTIR). No microplastics were found in any locations for rain samples. However, 243.54 MPs were detected from snow samples analyzed. MP detection may be affected by the volumes collected, preceding precipitation, environmental conditions, and the way samples were analyzed. The process and equipment used for MP analysis can also impact MP detection. Therefore, standardized protocols for analyzing and quantifying MPs from the falling precipitation are needed.